Singapore Eye Research Institute, Singapore and Singapore National Eye Centre, Singapore.
Invest Ophthalmol Vis Sci. 2013 Jan 23;54(1):708-13. doi: 10.1167/iovs.12-10844.
To compare the changes in iris volume with pupil dilation using anterior segment optical coherence tomography (AS-OCT) in eyes of subjects with different subtypes of primary angle closure.
This prospective study examined 44 fellow eyes (FA group) of subjects with previous acute primary angle closure (APAC), and 56 subjects (AC group) with chronic primary angle closure and/or primary angle closure glaucoma. All participants underwent gonioscopy and AS-OCT imaging. The iris volume, iris cross-sectional area, and pupil diameter were measured with custom semiautomated software. The main outcome variable analyzed was mean change in iris volume between light and dark conditions in a multivariate linear regression analysis.
Thirty-five eyes from the FA group (79.5%) and 50 eyes from the AC group (89.3%) were included in the final analysis. When going from light to dark, iris volume did not change significantly in eyes in the FA group (+1.50 ± 6.73 mm(3); P = 0.19), but decreased in the AC group by 1.52 ± 3.07 mm(3) (P < 0.001). This difference was significant (P = 0.01). On multivariate analysis after controlling for age, sex, baseline pupil diameter, and change in pupil diameter, age (β = -0.397; P < 0.001) and diagnostic category (AC versus FA group; β = 0.347; P < 0.001) were significant determinants of iris volume change.
With physiologic mydriasis, the iris volume decreased in eyes with chronic angle closure but remained unchanged in fellow eyes of APAC. Such variations in iris volume responses may influence the subtype of angle closure that develops.
使用眼前节光学相干断层扫描（AS-OCT）比较不同原发性闭角型青光眼亚型患者瞳孔散大时虹膜体积的变化。
本前瞻性研究共纳入 44 只眼（FA 组）的对侧眼，这些眼的主人曾患有急性原发性闭角型青光眼（APAC），以及 56 只眼（AC 组）的慢性原发性闭角型青光眼和/或原发性闭角型青光眼患者。所有参与者均接受房角镜检查和 AS-OCT 成像。使用定制的半自动软件测量虹膜体积、虹膜横截面积和瞳孔直径。主要观察指标为多元线性回归分析中明、暗光条件下虹膜体积的平均变化。
FA 组 35 只眼（79.5%）和 AC 组 50 只眼（89.3%）最终纳入分析。在 FA 组中，从明处到暗处，虹膜体积没有明显变化（增加 1.50±6.73mm3；P=0.19），但在 AC 组中减少了 1.52±3.07mm3（P<0.001）。这种差异具有统计学意义（P=0.01）。在控制年龄、性别、基线瞳孔直径和瞳孔直径变化后进行多元分析，年龄（β=-0.397；P<0.001）和诊断类别（AC 与 FA 组；β=0.347；P<0.001）是虹膜体积变化的显著决定因素。
在生理性瞳孔散大时，慢性闭角型青光眼眼的虹膜体积减小，而急性闭角型青光眼对侧眼的虹膜体积不变。这种虹膜体积反应的差异可能会影响闭角型青光眼的亚型发展。
